Nomenclature
CAS number: 16872-11-0
Hydrogen tetrafluoroborate; borofluoric acid; hydrofluoboric acid.
BF
4H; mol wt 87.81.
B 12.31%, F 86.54%, H 1.15%.
HBF
4.
Description and references
Prepd from H3BO3 + HF:
Fichter, Thiele, Z. Anorg. Allg. Chem. 67, 302 (1910); Mathers et al., J. Am. Chem. Soc. 37, 1516 (1915);
Funk, Binder, Z. Anorg. Allg. Chem. 155, 327; 159, 121 (1926); Sheintsis, J. Appl. Chem. USSR 13, 1101 (1940);
Wamser, Christian, J. Am. Chem. Soc. 70, 1209 (1948); Kwasnik in Handbook
of Preparative Inorganic Chemistry vol. 1, G.
Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) pp 221-222.
For other methods of prepn see H. S. Booth, D. R. Martin, Boron Trifluoride and Its Derivatives (New
York, 1949). Review: Sharp, Adv.
Fluorine Chem. 1, 68-128 (1960).
Properties
Liquid.
Poisonous. bp 130° (decompn). Miscible with water, alcohol. Strong acid.
nD20 of a 20% aq soln 1.3284. Heat of formn 388.5 kcal. Undergoes
limited hydrolysis in water to form hydroxyfluoborate ions; major
product is BF
3OH
. Pure HBF
4 may
be stored in glass vessels at room temps. Forms cryst salts wth metals.
The heavy metal salts and LiBF
4 and NaBF
4 are
very sol in water.
See Potassium
Tetrafluoborate about color phenomena appearing in concd
solns of fluoboric acid.
Caution
Strong caustic action on skin, mucous
membranes. Irritating to eyes, respiratory tract. Plating solns
contg fluoborates are considered toxic.Use
As catalyst for preparing acetals, esterifying cellulose;
to clean metal surfaces before welding; to brighten aluminum; as a
solute in electrolytes for plating metals such as chromium, iron,
nickel, copper, silver, zinc, cadmium, indium, tin, and lead (has
a high throwing power). Reagent for sodium in the presence of magnesium
and potassium ions; for making stabilized diazo salts (diazonium and
tetrazonium fluoborates). An 0.1 to 0.5% soln retards fermentation:
Homeyer,
Pharm. Ztg. 34, 761 (1889).